Adi Shankara (788 CE - 820 CE) was an Indian philosopher who consolidated the doctrine of Advaita Vedanta, the most influential sub-school of Vedanta. His teachings are based on the unity of the soul and Brahman, in which Brahman is viewed as without attributes. He hailed from Kalady of present day Kerala. Shankara travelled across India and other parts of South Asia to propagate his philosophy through discourses and debates with other thinkers. He founded four mathas ("monasteries"), which helped in the historical development, revival and spread of Advaita Vedanta. Adi Shankara is believed to be the organizer of the Dashanami monastic order and the founder of the Shanmata tradition of worship.